Tube-mill.



D. H. ATKINS.

TUBE MILL.

APPLIGATION FILED PBB.11, 1914.

Patented 32111.26, 1915.

VSN

IN VENTOR a/mf charged Withpebbles or balls.

' pebbles upon each other, upon thelining of the interior of the millDAVID n. Arxius, or' san rnancisco,

' risico centenaire, assieme To armies, Knorr.. e co., or sen rnANcIsco,L

CALIORNIA, A FIRM.

T aZZ'wtom 'it may concern.'

Be it known that I, DAVID H. ATKINs, a citizen of the United States,-residing inthe city and county of San Francisco and State ofCalifornia, have invented new and useful Improvements inTube-Mills, ofwhich the following is a specification. t

This invention' comprises improvements in the art of tube milling,Which-is, as at present practised, a process for pulverizing andgrinding ore by introducing this into a cylindrical or conicalcontainer, or a combination of both, revolving on its aXis and reducedin or grinding of the or by the pebbles through this container, the oreis Asize by the imp'ingement or cylinder.

ln' the cylindrical mill, large and small pebbles arrange themselvesat'random. ln the conical form of mill they arrange themselves naturallyso that" thelargest pebbles occupy the greatest diameter andthe smallestpebbles the smallest diameter, with the result that in the areacontaining` the greatest superimposed Weight there 'are leastpoints ofcontact to the cubic foot, and in the area containing the leastsuperimposed Weight, there are the greatest number of points of contactper cubic foot. To remedy these' alleged defects, l havedevised a tubemill Which'may be best described as a stepcone form, that is, dividedintotwo or more compartments, each ofa different diameter; the largerpebbles being retained inthe compartment 'of least diameter and theSmaller pebblesr passing or. being fed to compartments of successivelyAgreat diameter.

increased eiiiciency is claimed'for this device owing to the fact thatin the chamber containing larger pebbles the liner can be ribbed sogasto attain in the center a cascade of these larger pebbles which are moreeiiicient as percussion agents, due to their greater Weightandmomentum,while in the chambers of greater diameter this cascading or falling ofpebbles can be elimmated, 1f desired, and the maximum abrasive action`of the small' pebbles bey obtained by increase of points of contact.Where a fine, granular product is" desired rather than an .impalpablepowder'or slime', to. obtain the maximum lrapidity of discharge, and'toavoid the ne- Specicationof Letters Patent.

ycessity ef accomplished Patented Jan. 26, item5.

.fpplcetion ledFevbl'ualy lll, 2914.5. Serial No. 818,031.-

grinding the ore so fine as to enable 1t to` be carried off bysuspension only, apertures can bezmade in the plates forming the ends ofthei chambers at varying distances from the circumference. Mixedpebbles; can be introduced with the ore at the feed end of the mill andleft to arrange themselves; or the larger pebbles can besintroduced atthe feed end of the mill and the smaller-.pebbles at the discharge end.

he lnvention consists of the parts and the construction and combinationof parts as Iherelnafter more fully described and claimed, havingreference to the accompanyingdrawlngin which the figure is alongitudinal central section through the device.

he null is shown as having trunnion heads 2 and 3, open for the feed anddischarge of ore and pulp respectively. The m1ll is preferably formedof, or with, a plural1ty of successive chambers t, 5 and 6, of suitablelength and of different diameters, as shown.

rl`he principle involved in this invention is that, as the ore passesthrough the tube mill, a'fmore rapid and effective grinding is when thepebbles or balls of greatest diameter are confinedyto the chamber ofleast diameter (through which the ore must pass rst, and as the pebblesdecrease in size they are allowed to pass to chambers of increasingdiameter, thus increasing the number of points of abrasion as the oreparticles are reduced in size and as the Weight of .the superimposedmass becomes greater. It Willbe understood that where large balls orpebbles occupy a mill chamber or chambers, the interstices'vvill belikewise large, and when smaller balls or pebbles occupy a chamber theinterstic'es are ,likewise` smaller and the number of abrasive points ofcontact greater so that the imposed mass of grinding elements is farmore ye' ective upon the pulp passing between the small balls. Moreover,as the size of vthe pulp grain decreases, 'its fracture is more readilyeffected and a small ball or pebble-,twill be more economical than alarge Ione under the circumstances.` For this reason l have placed largeballs or pebbles in` the cchamber of least diameter, small balls orpebbles 9 in the chamber of greatest diameter, and intermediate balls orpebbles v'8in the' chamber of intermediate diameter. its` the grindingproceeds the pulp passes from one chamber, as 4, into the it@ vnextchamber, as 5, through apertures 10. l

The dividingflwalls maybe vprovided with centrall'screens 12 to checkthe passage of the over-sized balls-or pebbles from one chamber` toanother. From the chamber 5l theground material passes through wall 13to chamber 6 and` thence out.

Having thus described my invention, what I claim and .desire to secureby Letters Patent is- -f l.' An apparatus for milling consisting of ahorizontally disposed body having a relatively long end chamber, amiddle chamber of less length and considerably greater diameter thansaid end chambercommunicating with the latter, a. second end chamber ofless length and considerably greater diameter than said middlev chambercommunicating with the latter, balls in all of said chambers, the ballsin the middle chamber being of less diameter than the balls in theirstend chamber and the balls in the second end chamber being of lessdiameter than the balls. in the middle chamber, and

yse arate means for controlling'each of the sa1d communications betweenthe chambers, which -means retains the largest balls inthe first endchamber and permits the smaller and smallest balls to enter the middlechamber and retains the smaller balls in said middle chamber and allowsthe smallest balls to enter the second end chamber.

2. An apparatus for milling consisting of diameter than thev balls 'in'the middle cham' b'er. i

3. Anapparatus for milling consisting of a body having a series `ofintercommunieating chambers of successively increasing diameters anddecreasing lengths and balls of. varying diameters in the respectivechambers the balls in the chamber of least diameter having greaterdiameters than the remaining balls, the balls of least diameter being inthe chamber of'l greatest diameter whereby to progressively increaselthe grinding points and aggregate lgfeight of the balls in therespective chamers.

In testimony whereof I hare hereunto set myv hand in the presence of twosubscribing Witnesses.

DAVID H. ATKINS. Witnesses v JOHN H. HERRING,

W. W. HEALEY.

